This plugin redirects old command syntaxes for /effect, /gamemode, /summon.

/gamemode 1
is sent to server as
/gamemode creative

/gamemode sp @a
is sent to server as
/gamemode spectator @a

/effect @s 8
is sent to server as
/effect give @s jump_boost

/effect @s SPEED 30 8 true
is sent to server as
/effect give @s speed 30 8 true

/effect @s clear
is sent to server as
/effect clear @s

/summon Creeper
is sent to server as
/summon minecraft:creeper

/summon MinecartCommandBlock ~ ~ ~ {}
is sent to server as
/summon minecraft:command_block_minecart ~ ~ ~ {}

NBT Tag redirects for /summon is not yet supported(for example generic.attackSpeed becomes generic.attack_speed and convert Riding:{...} to Passengers:[{...}]) because I can not find an NBT tag parsing library.